Characterization of the key differential volatile components in different grades of Dianhong Congou tea infusions by the combination of sensory evaluation, comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry, and odor activity value

Abstract

Aroma is an important factor in evaluating tea infusion quality. In this study, the aroma quality of 44 Dianhong Congou tea infusions was classified into high-quality group and non-high-quality group according to the sensory evaluation. The volatile components were investigated by using headspace solid phase microextraction combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry. A total of 258 volatile components were identified, of which the three component types with the highest relative percentages were alcohols (17.05%), aldehydes (15.12%), and heterocycles (15.12%). Clear discrimination was achieved by orthogonal partial least squares discrimination analysis (R2Y = 0.94, Q2 = 0.82). In addition, 69 important differential compounds were identified based on variable importance in the projection value (VIP >1.0) and one-way ANOVA (p < 0.05). Moreover, seven common key odorants with odor activity values (OAVs) > 1 were screened out, including (E, E)-2,4-heptadienal, linalool, 1-octene-3-one, geraniol, β-myrcene, (Z)-4-heptenal, and nonanal. Aroma character impact value indicated that linalool performed a positively supportive role in the aroma quality of Dianhong Congou tea infusions, while (E, E)-2,4-heptadienal negatively affected the aroma quality. These results contribute to providing a theoretical support for directional processing of high-quality black tea.